This invention relates to a piston pin for pistons of reciprocating piston machine, particularly of internal combustion machines, which pin is I-shaped in cross-section and has flanges which are connected by a web and support the piston at the piston pin bosses and have outside surfaces which have the contour of an arc of a circle having an equal radius.
An important part of the development work, particularly for internal combustion engines, is concerned with the compact piston, which should be as light in weight as possible and should be able to transmit present-day high motor powers of, e.g., 65 H.P./1, without a sacrifice regarding oil consumption and blow-by and also in consideration of the increased requirements regarding smooth mechanical running, particularly in a cold state. Because the piston pins account for a substantial part of the oscillating masses of the power unit, lightweight alternatives consisting of steel, plastic, composite and ceramic piston pins reinforced by carbon fibers have been developed in the art and permit a saving in weight up to 25% or even 40% compared to a conventional piston pin of steel. The piston pins have an endurance limit which is sufficient for an igniting pressure PZ=60 bars. But their manufacture is much more expensive than the manufacture of the conventional piston pins of steel and for this reason they can be used at present only for special applications. Pending U.S. application 039,813 filed Apr. 14, 1987, and now U.S. Pat. No. 4,709,620 discloses a piston pin which is I-shaped in cross-section and its flanges have outside surfaces having a contour of an arc of a circle. That piston pin can be used with connecting rods of all kinds and is lighter by about 20% than a piston pin of steel whereas the expenditure is not appreciably increased.